Lyophilization installation

ABSTRACT

A lyophilization installation comprising a vacuum vessel having a plate rigidly fixed inside the vessel and upon which, in operation, a vibration bed is produced and particles of a product to be lyophilized are dried. Vibration means are provided and connected to the vessel for vibrating the vessel as a whole. The vacuum vessel is constructed to define, above the plate, an increasing flow cross-section for vapors liberated from the particles of the product.

O United States Patent [191 [111 3,733,716

Bonteil [4 1 May 22, 1973 54] LYOPHILIZATION INSTALLATION 3,616,542 11/1971 Rader ..34 92 4 3,521,373 7/1970 Pagnozzl ..34/92 [75] Invent France 3,289,314 12/1966 Porta ..34/92 [73] Assignee: Matsushita Electric Works, Ltd. 3,230,633 1/1966 Hamilton ..34/15 Osaka Japan 3,197,328 7/l965 Jung ..263/21 A [22] Filed: May 28, 9 Primary Examiner-Kenneth W. Sprague Assistant Examiner-James C. Yeung 1 A 1. 4 1 PP No l 8009 Atmrrzey-Woudhatfls, Blanchard & Flynn [30] Foreign Application Priority Data [57] ABSTRACT June 2, 1970 France ..7020098 A y phil z i in ll ion c mpri ing a vac um vessel having a plate rigidly fixed inside the vessel and 52 '11s. c1. ..34/92, 34/15, 34/164 p which. in Operation. a vibration bed is produced 511 1111. c1 ..F26b 13/30 and Particles of a Product to be lyophilized are dried- [58] Field of Search ..34/92, 5, 15, 164 Vibration means are Provided and connected to the vessel for vibrating the vessel as a whole. The vacuum [56] References Cited vessel is constructed to define, above the plate, an increasing flow cross-section for vapors liberated from UNITED STATES PATENTS the particles of the product.

3,465,452 9/1969 Rothmayr ..34/92 6 Claims, 2 Drawing Figures LYOPI-IILIZATION INSTALLATION The present invention relates to lyophilization installations.

A conventional lyophilization installation has a vacuum vessel inside which the particles of a product to be lyophilized are dried on a vibrating plate, and it frequently occurs that the particles of the product, particularly the smallest particles, are carried in the flow of water vapor from the vibrating plate and are lost, which obviously reduces the yield of the lyophilization installation. These particles of the product leaving the vibrating plate are not necessarily entrained in the flow of water vapor towards a stream trap, but, most frequently, are deposited on the inside walls of the vacuum vessel so that it is necessary for the vacuum vessel to be periodically cleaned.

The present invention seeks to overcome these disadvantages of the conventional lyophilization installations.

According to one particular aspect of the present invention, there is provided a lyophilization installation comprising a vacuum vessel, a plate rigidly fixed inside the vessel and upon which, in operation, a vibration bed is produced and particles of a product to be lyophilized are dried, and vibration means for vibrating the vessel as a whole.

As will be appreciated the particles of the product which are carried in the flow of vapor and are deposited on the inside walls of the vacuum vessel automaticall'y fall back onto the plate as a result of the vibration of the vessel Moreover, as it is not essential to provide the vibration means inside the vessel, as in the conventional lyophilization installation, the construction of the vessel is far simpler and a larger space remains therein available for the particles of the product and associated equipment such as, for example, heating elements.

The vacuum vessel is, preferably, so constructed as to define, above the plate, an increasing flow crosssection for vapor liberated from the particles of the product.

Vacuum vessels used at the present time are gener ally cylindrical in form and disposed horizontally, so that the plate may be placed in the bottom part of the vessel. It will be noted that the arrangement of the plate in the bottom part of the vessel is greatly facilitated by the fact that the vibration means need not necessarily be positioned with-in the vessel.

Thus, the particles of the product which are carried in the flow of vapor undergo an abrupt drop in speed and tend to fall back or return onto the plate by the action of gravity, or else are deposited on the walls of the vessel from which they return to the plate by the vibration of the vessel.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is an elevational and partly broken away view of a lyophilization installation according to the present invention; and

I FIG. 2 is a sectional viewon the line II-II of the lyophilization installation of FIG. 1.

A lyophilization installation according to the present invention and illustrated in the drawings is designed for the continuous treatment of a product (more particularly, although not so restricted, a food product) which has previously been frozen and divided into fine particles.

The installation comprises a vacuum vessel 1 of cylindrical shape and horizontally disposed. Inside the vessel 1 there is rigidly fixed a horizontal plate 2 adapted to support the particles of the product. The plate 2 is disposed in the bottom part of the vessel 1 and is rigidly connected to the side walls thereof by inclined ribs or rims 3 the purpose of which will be appreciated from the discussion given hereinafter. The frozen particles of the product to be lyophilized or dried are introduced into the vessel 1 through an inlet 4 and pass through a screen (not shown) and are discharged from the vessel through another screen (also not shown) and an outlet 5.

The vessel 1 rests on the ground by four feet 6 provided with elastic suspension elements 7 and is vibrated by external means (not shown) which may, for example, be motors with out-of-balance weights. The vibrations to which the vessel 1 is subjected are such that the particles of the product deposited on the plate 2 are transported from upstream (i.e. adjacent the inlet 4) to downstream (i.e. adjacent the outlet 5) in the form of a vibrating or fluidized bed 8.

Inside the vessel 1, on each side of the plate 2, there is disposed an upper heating plate 9 and a lower heating plate 10. These two heating plates are rigidly connected to fixed supports 11 by uprights 12 which pass through the walls of the vessel 1 in flexible connections 13 to ensure airtightness of the vessel. The water'vapor, freed from the particles of the product during its drying, is discharged through a top opening 14 also provided with a flexible connection 15, passing to a steam trap or condenser (not shown).

In the course of their transport from upstream to downstream on the plate 2, the particles of the product are dried by the heating plates 9 and 10 and the water vapor freed from them passes to the top opening 14.

It is known that when the flow of water vapor liberated from the particles of the product is very intensive certain particles, particularly the smallest particles, are carried from the vibrating bed 8 by the water vapor and tend to be deposited on the inside walls of the vessel 1 or else are entrained in the flow of water vapor to the steam trap.

In the lyophilization installation described above the entire vessel 1 is vibrated. The particles of the product liable to be deposited on the walls of the vessel 1 fall back automatically into the vibrating bed 8 as a result of the vibration of the vessel and with the aid of the inclined rims 3. The yield of this lyophilization installation is, therefore, improved and, in addition, as the inside walls of the vessel 1 remain clean, the vessel does not need to be cleaned as frequently as the vessels of conventional lyophilization installations.

It will finally be noted that, since the plate 2 is disposed in the bottom part of the vessel 1 this arrangement being made possible by the fact that the vessel has no vibration means disposed inside it the flow crosssection for water vapor liberated from the particles of the product first increases above the vibrating bed 8 and then decreases towards the top opening 14. Consequently, the particles of the product which may be suspended in the flow of water vapor and run the risk of being entrained in the flow of water vapor to the trap undergo an abrupt drop in speed and tend to return to the vibration bed 8 or contact the inside walls of the vessel 1, by the action of gravity.

Thus, in the lyophilization installation described above, the majority of the particles of the product leaving the vibration bed 8 rapidly return to it and, therefore, are not lost so that the yield of the lyophilization installation is considerably increased.

What we claim is:

1. A lyophilization installation, comprising:

wall means defining a vessel having a substantially closed vacuum chamber, said wall means including rigidly interconnected top, bottom, side and end wall portions; plate means disposed within said vacuum chamber and rigidly fixed to said wall means, said plate means during operation of said installation defining a vibration bed for product particles to be dried;

inlet means associated with said wall means and communicating with said plate means adjacent one end thereof for permitting product particles to be supplied to said plate means;

outlet means associated with said wall means and disposed adjacent the other end of said plate means for permitting the dried particles to be removed from said vacuum chamber;

vibration means operatively interconnected to said wall means for vibrating said vessel as a whole together with the plate means rigidly fixed thereto; vacuum means disposed externally of said vessel; and conduit means operatively connected between said vacuum means and said vessel for permitting creation of at least a partial vacuum within said chamher.

2. An installation according to claim 1, wherein said vessel as defined by said wall means is elongated as it extends between opposed end wall portions, said inlet means being disposed adja-cent one end wall portion and said outlet means being disposed adjacent the other end wall portion, and the side wall portions in the vicinity of said plate means defining above the plate means an increasing flow cross-sectional area for the vapors liberated from the particles contained in the fluidized bed.

3. An installation according to claim 1, wherein said vessel includes an elongated substantially cylindrical wall member disposed with its longitudinal axis extending substantially horizontally and defining the top, bottom and side wall portions of said vessel.

4. An installation according to claim 3, wherein said plate means is disposed substantially horizontal and extends substanti-ally longitudinally of said cylindrical wall member, said plate means being positioned within the lower half of said cylindrical wall member so that the flow area above said plate means increases in an upward direction away from said plate means.

5. A installation according to claim 4, wherein said conduit means is connected to said cylindrical wall member adjacent the upper portion thereof at a location disposed substantially midway between the inlet and outlet end of said plate means, and said conduit means including flexible connecting means associated therewith for permitting said vessel to be vibrated as a whole while preventing said vibration from being transmitted through said conduit means to said vacuum means.

6. An installation according to claim 1, further including first and second heating means disposed respectively above and below said plate means and extending substantially coextensively therewith. 

2. An installation according to claim 1, wherein said vessel as defined by said wall means is elongated as it extends between opposed end wall portions, said inlet means being disposed adja-cent one end wall portion and said outlet means being disposed adjacent the other end wall portion, and the side wall portions in the vicinity of said plate means defining above the plate means an increasing flow cross-sectional area for the vapors liberated from the particles contained in the fluidized bed.
 3. An installation according to claim 1, wherein said vessel includes an elongated substantially cylindrical wall member disposed with its longitudinal axis extending substantially horizontally and defining the top, bottom and side wall portions of said vessel.
 4. An installation according to claim 3, wherein said plate means is disposed substantially horizontal and extends substanti-ally longitudinally of said cylindrical wall member, said plate means being positioned within the lower half of said cylindrical wall member so that the flow area above said plate means increases in an upward direction away from said plate means.
 5. A installation according to claim 4, wherein said conduit means is connected to said cylindrical wall member adjacent the upper portion thereof at a location disposed substantially midway between the inlet and outlet end of said plate means, and said conduit means including flexible connecting means associated therewith for permitting said vessel to be vibrated as a whole while preventing said vibration from being transmitted through said conduit means to said vacuum means.
 6. An installation according to claim 1, further including first and second heating means disposed respectively above and below said plate means and extending substantially coextensively therewith. 